Three inks that will never ever ever (well, maybe) make it into any of my pens.
We’ll start with Organics Studio Mercury in the middle. Turns out that after sitting for awhile, this ink solidified – well, actually, it gellified (it’s a word).  You can actually see the clumps in the third swab of this really pretty color.
Organics Studio Cobalt is guilty by association. I know, I know. I could try it with a glass dip pen, perhaps. It is a really pretty color – especially when it’s laid down in three layers, yes?
Noodler’s Rochmaninoff. I bought a sample of this from Goulet Pens (love them!) and it’s clear this isn’t like other inks. I had to shake the vial to mix it all up and even then, it looked – suspicious – like something I wouldn’t want to put in a pen. But. When I swabbed it, no problem – perfectly smooth and kinda pretty (in a Pepto kind of way). And look at the glow – pretty, right? I think I’m going to get brave sometime and test this one. Maybe. 
Are there ink brands you just won’t use? Have you ever changed your mind and it worked out ok? Or (yikes) didn’t work out?